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TT: Fachverband Tiefe Temperaturen
TT 40: Superconductivity: Qubits 1
TT 40.12: Talk
Wednesday, April 3, 2019, 12:30–12:45, H48
Qubit Measurement by Multichannel Driving — Joni Ikonen1, •Jan Goetz1, Jesper Ilves1, Aarne Keränen1, Andras M. Gunyho1, Matti Partanen1, Kuan Y. Tan1, Dibyendu Hazra1, Leif Grönberg2, Visa Vesterinen1,2, Slawomir Simbierowicz2, Juha Hassel2, and Mikko Möttönen1 — 1QTF Centre of Excellence, Department of Applied Physics, Aalto University, P.O. Box 15100, FI-00076 Aalto, Finland — 2VTT Technical Research Centre of Finland, QTF Center of Excellence, P.O. Box 1000, FI-02044 VTT, Finland
We theoretically propose and experimentally implement a method of measuring a qubit by driving it close to the frequency of a dispersively coupled bosonic mode [1]. The separation of the bosonic states corresponding to different qubit states begins essentially immediately at maximum rate, leading to a speedup in the measurement protocol. Also the bosonic mode can be simultaneously driven to optimize measurement speed and fidelity. We experimentally test this measurement protocol using a superconducting qubit coupled to a resonator mode. For a certain measurement time, we observe that the conventional dispersive readout yields close to 100 % higher average measurement error than our protocol. Finally, we use an additional resonator drive to leave the resonator state to vacuum if the qubit is in the ground state during the measurement protocol. This suggests that the proposed measurement technique may become useful in unconditionally resetting the resonator to a vacuum state after the measurement pulse.
[1] Ikonen, et al., arXiv 1810.05465